Carson Wandering Skipper (Pseudocopaeodes eunus obscurus) 5-Year Review: Summary and Evaluation © B. Moose Peterson, used with permission. U.S. Fish and Wildlife Service Nevada Fish and Wildlife Office Reno, Nevada August 27, 2012 5-YEAR REVIEW Carson wandering skipper (Pseudocopaeodes eunus obscurus) I. GENERAL INFORMATION Purpose of 5-Year Reviews: The U.S. Fish and Wildlife Service (Service) is required by section 4(c)(2) of the Endangered Species Act (Act) to conduct a status review of each listed species at least once every 5 years. The purpose of a 5-year review is to evaluate whether or not the species’ status has changed since it was listed (or since the most recent 5-year review). Based on the 5-year review, we recommend whether the species should be removed from the list of endangered and threatened species, be changed in status from endangered to threatened, or be changed in status from threatened to endangered. Our original listing of a species as endangered or threatened is based on the existence of threats attributable to one or more of the five threat factors described in section 4(a)(1) of the Act, and we must consider these same five factors in any subsequent consideration of reclassification or delisting of a species. In the 5-year review, we consider the best available scientific and commercial data on the species, and focus on new information available since the species was listed or last reviewed. If we recommend a change in listing status based on the results of the 5-year review, we must propose to do so through a separate rule-making process defined in the Act that includes public review and comment. Subspecies Overview: As summarized from the recovery plan for this subspecies (Service 2007), the Carson wandering skipper (Pseudocopaeodes eunus obscurus, CWS) is a small butterfly in the subfamily Hesperiinae (grass skippers). Carson wandering skipper habitat is characterized as lowland grassland habitats on alkaline substrates. Occupied areas are located in a small region east of the Sierra Nevada in northwestern Nevada and northeastern California. These areas are characterized by having an elevation of less than 1,524 meters (m) (5,000 feet (ft)), presence of Distichlis spicata (L.) Greene (saltgrass) (Hickman 1993), nectar sources in open areas near springs or other water sources, and a possible association with geothermal activity. At the time of listing in 2001, two extant populations were known, one in Washoe County, Nevada, and one in Lassen County, California. A third known population, from Carson City, Carson City County, Nevada, is considered extirpated as of 1998. In 2004, one additional population was located south of Carson City, along the Carson River in Douglas County, Nevada. In 2005, a second population in Washoe County was confirmed. Therefore, there are four extant populations of the CWS. Methodology Used to Complete This Review: This review was prepared by the Nevada Fish and Wildlife Office (NFWO), following the Region 8 guidance issued in March 2008. We used information from the recovery plan and surveys conducted by experts who have been monitoring various localities of this subspecies. The 2 recovery plan and information available in our files were our primary sources of information used to update the subspecies’ status and threats. We received one correspondence from the public (State of California, Department of Justice) in response to our Federal Register notice initiating this 5-year review. This 5-year review contains updated information on the subspecies’ biology and threats, and an assessment of that information compared to that known at the time of listing. We focus on current threats to the subspecies that are attributable to the Act’s five listing factors. The review synthesizes all this information to evaluate the listing status of the subspecies and provide an indication of its progress towards recovery. Finally, based on this synthesis and the threats identified in the five-factor analysis, we recommend a prioritized list of conservation actions to be completed or initiated within the next 5 years. Contact Information: Lead Regional Office: Larry Rabin, Deputy Division Chief for Listing, Recovery, and Habitat Conservation Planning, Region 8, Pacific Southwest (916) 414-6481. Lead Field Office: Marcy Haworth, Nevada Fish and Wildlife Office, (775) 861-6300. Cooperating Field Office: David Kelly, Sacramento Fish and Wildlife Office, (916) 414-6492. Federal Register (FR) Notice Citation Announcing Initiation of This Review: A notice announcing initiation of the 5-year review of this taxon and the opening of a 60-day period to receive information from the public was published in the Federal Register on March 5, 2008 (73 FR 11945, Service 2008). We received one response to the Federal Register notice regarding this subspecies. Listing History: Emergency Listing FR Notice: 66 FR 59537 Date of Emergency Rule: November 29, 2001 Entity Listed: Carson wandering skipper (Pseudocopaeodes eunus obscures), an insect subspecies Classification: Endangered Final Listing FR Notice: 67 FR 51116 Date of Final Listing Rule: August 7, 2002 Entity Listed: Carson wandering skipper (Pseudocopaeodes eunus obscures), an insect subspecies Classification: Endangered Review History: There have been no 12-month status reviews, 5-year reviews, or other relevant documents that contain a five-factor analysis and conclusion previously completed for this subspecies. 3 Subspecies’ Recovery Priority Number at Start of 5-Year Review: The recovery priority number for the CWS is 3C according to the Service’s 2011 Recovery Data Call for the NFWO, based on a 1-18 ranking system where 1 is the highest-ranked recovery priority and 18 is the lowest (Endangered and Threatened Species Listing and Recovery Priority Guidelines, 48 FR 43098, September 21, 1983). This number indicates that the taxon is a subspecies that faces a high degree of threat and has a high potential for recovery. The “C” indicates conflict with construction or other development projects or other forms of economic activity. Recovery Plan Name of Plan: Recovery Plan for the Carson Wandering Skipper (Pseudocopaeodes eunus obscurus) Date Issued: June 14, 2007 II. REVIEW ANALYSIS Application of the 1996 Distinct Population Segment (DPS) Policy The Act defines “species” as including any subspecies of fish or wildlife or plants, and any distinct population segment (DPS) of any species of vertebrate wildlife. This definition of species under the Act limits listing as DPSs to species of vertebrate fish or wildlife. Because the subspecies under review is an invertebrate, the DPS policy is not applicable, and the application of the DPS policy to the subspecies’ listing is not addressed further in this review. Information on the Subspecies and its Status Subspecies Biology and Life History Little is known about the life history and ecology of the CWS. During summer (June and July), females lay their cream-colored eggs on Distichlis spicata, the larval host plant (Garth and Tilden 1986, Scott 1986). The CWS apparently requires D. spicata with succulent, green leaves from March through June to complete its life cycle. Limited observations have been made of the early life stages of the CWS. However, the CWS’s life cycle is likely similar to other species and subspecies of the subfamily Hesperiinae. Larvae (caterpillars) of the Hesperiinae live in silked-leaf nests, and some species make their nests partially underground; larvae generally hibernate during winter (Scott 1986). Carson wandering skipper larvae have a light green body with a distinctive black collar below the head (Honey Lake Conservation Team (HLCT) 2006); the head is a rusty brown orange color. Some larvae may be able to extend their period of diapause (a natural state of suspended development at any life stage) for more than one season depending on the individual and environmental conditions (P. Brussard, University of Nevada Reno (UNR), pers. comm. 2001). Generally, pupae rest in the larval nest (Scott 1986). After several instar stages, the pupae emerge as adults in May or June (Sanford 2006a). The life span of an adult CWS is possibly 1-2 weeks, but they may live longer where abundant nectar sources exist with minimal habitat disturbance (Sanford 2006a). 4 Carson wandering skippers may differ from other Pseudocopaeodes eunus subspecies in producing only one brood per year during the June to mid-July flight season (Austin and Emmel 1998). The other subspecies may produce a second brood from late July to late September (Austin and Emmel 1998). During 1998 CWS surveys (Brussard et al. 1999), the formerly occupied Carson City site and the two occupied sites (Washoe County, Nevada; Lassen County, California) were visited in June and July and again in August and September to look for second broods; none were found. Spatial Distribution The subspecies occupies areas located in a region east of the Sierra Nevada in northwestern Nevada and northeastern California at elevations of less than 1,524 m (5,000 ft). The subspecies' distribution likely represents a remnant of a more widely distributed complex of populations in the western Lahontan Basin (Brussard et al. 1999). The CWS was first collected in Carson City in 1965 north of U.S. Highway 50 in Carson City (Ormsby) County, Nevada; several years later, a northern extension of this population was discovered (Brussard et al. 1999). The Carson Hot Springs drainage meanders through this general area. The site supports Distichlis spicata and areas of Thelypodium crispum (native mustard), the only known nectar source present. Habitat at this site has been greatly modified since 1965, primarily due to drainage manipulations for residential and commercial development (Brussard et al. 1999). In the 1990’s, available habitat was reduced to approximately 8 hectares (ha) (20 acres (ac)) (Brussard et al. 1999) and completely surrounded by development. Highway construction completed in 2006 impacted an estimated 2 ha (6 ac) of CWS habitat remaining within the site (P.